An armored U.S. Embassy vehicle is checked by military personal after it was attacked near Tres Marias, Mexico, in August. (AP)
(AP2012)

U.S. agents on assignment in Mexico, where they are helping the local authorities go after violent drug cartels, are not allowed to carry weapons for their own protection, a situation that one lawmaker says could turn into “another Benghazi.”

Because the official role of U.S. agents south of the border is limited to intelligence gathering and training their Mexican counterparts, they are barred by Mexico from carrying weapons. The danger they face was underscored last month, when 15 Mexican National Police were arrested in connection with the attempted murder of two CIA agents in August.

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“I don't want another Benghazi, absolutely do I feel our agents should be armed," Rep. Michael McCaul (R-Texas), the incoming chairman of the House Committee on Homeland Security, told FoxNews.com.

U.S. agencies involved in intelligence and training operations in Mexico include the CIA, FBI, Drug Enforcement Administration and others. Their presence has increased since the launching of the 2008 Merida Initiative, in which American operatives help Mexican law enforcement officials go after the violent and ruthless Mexican drug cartels, according to law enforcement sources.

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President Obama gave tacit approval to Mexico’s prohibition against U.S. agents carrying weapons in March 2011, following the ambush killing of ICE agent Jaime Zapata and the wounding of his partner, Victor Avilla.

"There are laws in place in Mexico that say our agents should not be armed," Obama said.

And DEA spokesman Michael Rothermund said it’s for Mexico to decide if American agents can carry guns in Mexico, not the U.S.

"The Drug Enforcement Administration respects the sovereignty and rules of the Government of Mexico that says United States Law Enforcement is not allowed to carry firearms," Rothermund said.

But U.S. lawmakers are concerned that law enforcement agents are being put in harm’s way without the ability to defend themselves despite working under the assumed protection of diplomatic association.

A CIA spokesman would neither confirm nor deny the presence of agents in Mexico Aug. 24, when the attempted murders took place. But published reports say the agents were driving in a black SUV with U.S. diplomatic plates, heading to a remote military installation with a Mexican naval official when they were fired upon. The assailants, who fired more than 150 rounds from AK-47s, were later identified as Mexican federal police officers.

The gunmen were wearing civilian clothes and driving private cars when they shot at the SUV, but then changed into uniform and brought patrol cars when investigators arrived at the scene, according to Mexican authorities. One officer was charged with making false statements while five others were accused of covering up the attack.

It was only the latest attempt to kill a U.S. agent.

In February 2011, two agents from Immigration and Customs Enforcement, also in a vehicle with U.S. diplomatic plates, were ambushed at what was thought to be a military road block. Zapata was killed and Avilla was wounded.

An embassy official and her husband were killed in Ciudad Juarez in March 2010.

The last DEA agent killed in Mexico was Enrique "Kiki" Camarena, who was tortured and beaten to death in 1985 after he was kidnapped by Mexican police officers allegedly on the payroll of drug kingpin Miguel Angel Felix Gallardo. Gallardo trained as a Mexican Judicial Federal Police agent.

One federal agent told FoxNews.com he knows several colleagues who carry concealed weapons in Mexico despite the prohibition. While it gives them added protection, they fear that using the weapons – even in an emergency situation – could land them in severe diplomatic and legal straits.

McCaul said he is uncomfortable with the level of violence in Mexico, which is only worsened by the layers of corruption.

"You can't trust the police on the local but it is better on the federal level, but the corruption is still there," McCaul said, referring to the August arrests of the Mexican Federal Police in connection with the August attack on the CIA agents.

A Mexican government official said the policy is in place to control the number of weapons in the country. He also said that given the recent spate of cross-border shootings by U.S. Border Patrol there is a sentiment that similar instances would occur deeper in the country with U.S. agents on assignment.

"It's a wider and sensitive issue of our sovereignty having foreign agents armed on our soil," said the Mexican official.

It is unlikely this policy will change under Enrique Pena Nieto, who was inaugurated Saturday as Mexico's new president.